Requirement of a soluble intracellular factor for activation of transient receptor potential A1 by pungent chemicals: Role of inorganic polyphosphates
Requirement of a soluble intracellular factor for activation of transient receptor potential A1 by pungent chemicals: Role of inorganic polyphosphates
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DOI：
10.1523/jneurosci.0623-07.2007
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发表时间：
2007-06-13
影响因子：
5.3
通讯作者：
Cavanaugh, Eric J.
中科院分区：
文献类型：
--
作者：
Kim, Donghee;Cavanaugh, Eric J.
刺激性化学物质，如异硫氰酸烯丙酯(AITC)、肉桂醛和大蒜素，通过直接激活感觉神经元表达的瞬时受体电位A1(TRPA1)而产生伤害性感觉。在这项研究中，我们发现，在吸管或浴液中加入刺激性化学物质很容易激活细胞贴附贴片中的TRPA1，但在由内而外或由外而外的贴片中则不能激活TRPA1。因此，需要一种可溶性的胞浆因子来激活TRPA1。N-乙基马来酰亚胺、(2-氨乙基)-甲烷硫代磺酸盐、2-氨基乙氧基二苯基硼酸酯和三硝基苯酚，这些已知激活TRPA1的化合物也未能从内向外激活它。为了确定支持刺激性化学物质激活TRPA1的因素，我们筛选了类似于30个已知的调节离子通道的细胞内分子。其中，焦磷酸(PPI)和聚三磷酸(PPPI)被发现支持刺激性化学物质激活TRPA1。结构-功能研究表明，含有至少四个磷酸盐基团的无机聚磷酸盐(Polyp(N)，其中n=磷酸盐的数量)是高效的(PolyP4近似PolyP65，PolyP45近似PolyP25>；PPPI>；PPI)，K-1/2值在0.2-2.8 mm之间。肌醇-三磷酸和肌醇-六磷酸也部分支持AITC对TRPA1的激活。具有三个磷酸基团的ATP、GTP和磷脂酰肌醇-4，5-二磷酸不支持TRPA1的激活。从三叉神经节神经元细胞体记录到的TRPA1对刺激性化学物质的敏感性表现出类似的行为；除非存在聚磷酸盐，否则在由内向外的斑块中没有观察到激活。这些结果表明，TRPA1需要一种细胞内因子来采用对刺激性化学物质敏感的功能构象，并提示多聚磷酸可能部分地起到这种因子的作用。
Pungent chemicals such as allyl isothiocyanate ( AITC), cinnamaldehyde, and allicin, produce nociceptive sensation by directly activating transient receptor potential A1 ( TRPA1) expressed in sensory afferent neurons. In this study, we found that pungent chemicals added to the pipette or bath solution easily activated TRPA1 in cell-attached patches but failed to do so in inside-out or outside-out patches. Thus, a soluble cytosolic factor was required to activate TRPA1. N-Ethylmaleimide, ( 2-aminoethyl)-methane thiosulfonate, 2-aminoethoxydiphneyl borate, and trinitrophenol, compounds that are known to activate TRPA1, also failed to activate it in inside-out patches. To identify a factor that supports activation of TRPA1 by pungent chemicals, we screened similar to 30 intracellular molecules known to modulate ion channels. Among them, pyrophosphate ( PPi) and polytriphosphate ( PPPi) were found to support activation of TRPA1 by pungent chemicals. Structure-function studies showed that inorganic polyphosphates ( polyP(n), where n = number of phosphates) with at least four phosphate groups were highly effective ( polyP4 approximate to polyP65 approximate to polyP45 approximate to polyP25 > PPPi > PPi), with K-1/2 values ranging from 0.2 to 2.8 mM. Inositol-trisphosphate and inositol-hexaphosphate also partially supported activation of TRPA1 by AITC. ATP, GTP, and phosphatidylinositol-4,5-bisphosphate that have three phosphate groups did not support TRPA1 activation. TRPA1 recorded from cell bodies of trigeminal ganglion neurons showed similar behavior with respect to sensitivity to pungent chemicals; no activation was observed in inside-out patches unless a polyphosphate was present. These results show that TRPA1 requires an intracellular factor to adopt a functional conformation that is sensitive to pungent chemicals and suggest that polyphosphates may partly act as such a factor.